I have a simple port triggering setup that doesn't seem to work in build 52 and 54. I haven't found any reliable way of testing it - if anybody has any suggestions, please let me know.

My rule is simple: trigger port is 2000, forwarded port 4000.
From lan I make a connection to the internet - bar.com 2000. Port 4000 should be forwarded now to the host that made the connection but it's not. My attempts to connect to it (from the lan) fail. However, if I forward the port manually, it works without a problem.
Is there something that I'm missing here? I tried to figure out what ports are opened, and which aren't to no avail.
I have changed nat loopback from forwarded to all but things remain the same.

I recall this working for me on tomato, with the same setup about 8-12 months ago.

Any clues?

P.S. Is there any way to see what ports are opened - iptables -L displays the rules but I'm interested to know the triggered ports as well (in case they are opened or not).
Thanks!